The job of comparing two electrical quantities to one another occurs in many fields of technology. For example, these comparisons are thus a foundation of electrical mensuration technology. Threshold equations can also be technically realized with the assistance of evaluator circuits.
Methods that compare electrical quantities with the assistance of operational amplifiers are known and are often employed (U. Tietze, Ch. Schenk, Halbleiterschaltungstechnik, 9th Edition Springer Verlag, 1990, pages 132 through 143). A significant disadvantage of these methods is comprised in the conversion of static dissipated power and in the comparatively large space requirement of such circuits, particularly when a great number of them are required. A further possibility of implementing an evaluation of two electrical quantities is comprised in the employment of a neuron MOS inverter, whereby the reference quantity to which another electrical quantity is to be compared is determined by the switching threshold of the neuron MOS inverter (T. Shibata and T. Ohmi, "A function MOS Transistor featuring gate-level weighted sum and threshold operations", IEEE Trans. Electron Devices, 39, 1992, pages 1444-1455). The employment of a neuron MOS inverter in this context exhibits a number of disadvantages. A static quadrature-access current component for all potentials flows on the floating gate .phi..sub.F with V.sub.SS +V.sub.th,n &lt;.phi..sup.F &lt;V.sub.DD -V.sub.th,p, this corresponding to the normal case during operation as threshold gate. Moreover, it is necessary to govern the technology parameters extremely well, so that the threshold dimensioning corresponds to the desired behavior, i.e. that narrow tolerances of the threshold voltage must be adhered to.
A circuit arrangement for the comparison of two electrical currents wherein two co-coupled inverter units are provided is disclosed by (J. A. Hidalgo-Lopez et al., New Types of Digital Comparators, IEEE Internat. Symposium of Circuits and Systems (ISCAS), Seattle, April 30 through May 3, 1995, Vol. 1, pp. 29-32). The electrical quantities to be compared are respectively impressed at the outputs of the inverter units. The source terminals of the two inverter units are connected to one another and are connected to ground via a clock transistor.
U.S. Pat. No. 3,950,636 discloses two comparison units provided in a multiplier cell.